Synthesen in der Polymyxin-Reihe 9. Mitteilung. Synthese von Polymyxin B1†

The synthesis of the cycloheptapeptide 7α (Fig. 4) containing the α,γ-diaminobutyric acid residues only in the L form, and its cristallization as pentaphosphate are reported. This latter substance proved to be in all respects identical with the cristalline penta- phosphate of natural polymyxine B1.